OpenSky - Behind the Scenes

         ·

The OpenSky Network is a community-based receiver network which continuously collects air traffic surveillance data. Unlike other networks it keeps collected data forever and serves as a data provider for researchers all around the globe. OpenSky’s data can be harnessed for very different purposes ranging from desaster analysis to meteological measurements. Because it is impossible to be aware of all use cases it is important to store all raw data in the hope that it will be useful at some point.


OpenSky Tech Stack I - Architectural Overview

         ·

This is the first post of my series about the OpenSky Network. We will have a look at OpenSky’s architecture and the requirements which supported this choice. Requirements We want to collect every single Mode S message emitted all over the globe. – OpenSky’s objective OpenSky formerly started as a research project to collect ADS-B and and later on Mode S data for security research. Due to the lack of available sources, researchers at armasuisse Science and Technology put up a few receivers to collect messages in a MySQL database.


Remove MP3 watermark

              · ·

When downloading mp3s from Amazon they contain a watermark in the ID3 v2 frame “PRIV”. To remove it, you can use eyeD3 (python2-eyed3 package in Arch Linux):


Fix Urxvt Terminfo

             

This is for rxvt-unicode users. If applications like top or screen complain on a remote machine with a message like open terminal failed: missing or unsuitable terminal: rxvt-unicode-256color then the proper terminfo in /usr/share/terminfo is missing. To address this problem, first create a terminfo file in a urxvt session on your local machine. infocmp -L rxvt-unicode-256color > urxvt.tic Copy the file to the remote host and run tic urxvt.


Starting systemd Services when Encrypted Device is plugged in

              ·

Problem: You want to start a service only once an encrypted harddrive is plugged in. On our embedded iconnect box, we run an mpd whose music collection is stored on an external, encrypted hdd. The mpd should only start when the device is plugged in, since otherwise it would rescan its collection every time the hdd is not present. To achieve that, we can use systemd’s ability to define dependencies.


Fix Broken Standby

              ·

After setting my ThinkPad to standby mode it never woke up as I expected. In most cases I had to poweroff the whole machine, which is very ugly. I am using Ubuntu 8.04 and discovered the issue has not been fixed in the new 8.10 release.

In these days I read something interesting in the Ubuntu Forum


1920x1200 Resolution with Intel 945GM

             

I had some trouble to get the maximum resolution for my monitor, using the VGA output of my Thinkpad. I’m running Ubuntu Hardy which uses the xserver-xorg-video-intel driver by default. This can be combined with xrandr to manage all your monitor/resolution settings without restarting all the time.

First of all I had a look at the possible resolutions:


Open URLs from Terminal (rxvt)

             

While using the terminal based IRC client “irssi” I faced the problem that I always had to copy and paste URLs to my webbrowser.

After a little research I found a way to open URLs just by clicking the mouse wheel. It’s quite easy: you need a special terminal: rxvt-unicode (urxvt).


Reduce CD-ROM Speed

             

Have you ever asked yourself why your DVD Player is much more quiet than the CD-ROM drive in your PC? It’s because playing audio/video just needs a reduced reading performance which calms down your drive a lot.


Concatenate Multiple PDF Files

              ·

Some of you are familiar with the situation when you have got a bunch of pdf files you want to print. Especially at university there are a lot of different lecture notes waiting to be put on paper. Printing every single file can be annoying and cost too much time (and money if you pay an extra charge for the print job). Facing this problem I found out that there is a way to put multiple pdf files together using ghostview (which should be included in every linux distribution).